Impact of sexual reproduction on adaptive dynamics of Z. tritici populations driven by R-AVR interaction
Little is actually known about the impact of host immunity on sexual reproduction in Zymoseptoria tritici but also reciprocally about the impact of sexual reproduction on epidemiological processes and adaptive dynamics of pathogen populations driven by R-AVR interactions. An experiment investigating different scenarios of Z. tritici crosses on wheat according to the virulence or avirulence status of the parents against a Stb gene showed that parents did not require preliminary symptomatic asexual infection to mate. This change in the population genetics baseline of Z. tritici deserves particular attention in heterogeneous wheat covers (cultivar mixtures or landraces), where interactions between virulent and avirulent strains are favoured. Depending on the conditions, crosses could either limit resistance breakdown by maintaining the frequency of virulent strains below a certain threshold, or conversely, increase it, even promoting the emergence of multi-virulent strains.